For the study, the researchers looked at about 86,000 people who survived the bombing of Nagasaki.

Not all of the study subjects had lived very close to the blast site at the time, and some of them had normal rates of MDS.

Statistically, the rates of MDS literally radiated outward from the blast site, with people's risk of getting radiation-related MDS rising by up to 88% per kilometre of proximity to the explosion.

In total, 198 of the people who had survived the Nagasaki blast developed MDS between 1985 and 2004.

David Brenner, head of the Center for Radiological Research at Columbia University in New York, who was not involved in the research, said that the recent study gave credence to the fact that radiation even at moderately low doses was hazardous.

He said the study also showed that the diseases people got from radiation were not limited to cancer.

The study is also relevant for people considering the possible harm of modern radiation sources used to probe the human body, like x-rays and their modern derivative, computed-tomography scanning (CT).

Every CT scanner emits a different level of radiation and, on average, having several CT scans could still theoretically equal the same amount of radiation exposure as people who today live near the site where Nagasaki was hit.

Because the number of CT scans doctors perform has been increasing recently, doctors are worried that this increase might contribute to people getting cancer.

Rebecca Smith-Bindman, of the University of California in San Francisco, said that people who had MDS also had a leukaemia risk, and that the study should increase people's efforts to reduce radiation exposure.

The atomic bombings of Japan killed an estimated 90,000–166,000 people in Hiroshima and 60,000–80,000 in Nagasaki, with roughly half the deaths occurring on the day of the explosion in both cities. Most were civilians.

US researchers estimate that 15–20% died from radiation sickness, 20–30% from flash burns, and 50–60% from other injuries, compounded by illness.